<!DOCTYPE html>
<html lang="en">
<head>
    <style>
        .demo a{
            float:left;
            display:block;
            height:50px;
            width:50px;
            border-radius:10px;
            background:#2700ff;
            text-align:center;
            color:gainsboro;
            text-decoration:none;
            margin-right:5px;
            font:bold 20px/50px Arial;
        }
        /*属性名，属性名=属性值（正则）
        =绝对等于
        *=包含这个元素
        ^=以这个开头
        $=以这个结尾
        */
        /*存在id属性的元素		a[]{}
            a[id]{
                background:yellow;
            }
        id=first的元素
            a[id=first]{
                background：#63ff23
            }
        class中有links的元素
            a[class/*="links"]{
                background:yellow;
            }
        选中href中以http开头的元素
            a[href^=http]{
                background:yellow;
            }
        */
        a[href$=jpg]{
            background:yellow;
        }
    </style>
</head>
<body>
<p class="demo">
    <a href="http://www.baidu.com" class="links item first" id="first">1</a>
    <a href="http://blog.kuangstudy.com" class="links item active" target="_blank" title="test">2</a>
    <a href="images/123.html" class="links item">3</a>
    <a href="images/123.png" class="links item">4</a>
    <a href="images/123.jpg" class="links item">5</a>
    <a href="abc" class="links item">6</a>
    <a href="/a.pdf" class="links item">7</a>
    <a href="/abc.pdf" class="links item">8</a>
    <a href="abc.doc" class="links item">9</a>
    <a href="abcd.doc" class="links item last">10</a>
</p>
</body>
</html>
